1. Field of the Invention
The invention concerns a fuel cell, especially a direct methanol fuel cell.
2. Description of the Related Art
It is known that the output of fuel cells can be increased by connecting their power-generating microreactors in parallel or in series. For example, WO 00/54358 explains the structure of fuel cell modules in which many individual microreactors are arranged in each plane of a frame and are connected in series. The surfaces of the individual electrodes are formed as cathodes and are in direct contact with each other, and the coaxially inner anodes of the individual microreactors are connected with each other at an end face of the module.
Individual modules of this type can in turn be cascade-connected and/or series-connected.
WO 03/005466 discloses another output-enhancing arrangement of bundles of microreactors, likewise with a coaxial structure. Alternatively, it is explained that the microreactors can be replaced by microreactors with a common outer electrode, so that the basic coaxial structure is preserved.
Due to the coaxial design of these microreactors, the built-up electric potential is generally tapped at the axial end of such a microreactor. The length of the microreactor thus also determines the electric power output.
Especially if so-called tubular assemblies are used as microreactors, the mechanical stability is usually low, and for this reason the length of this type of microreactor is limited, and the power output or the level of voltage that can be tapped is correspondingly low.